Hi Reggie,

Doh! Yes, of course, you are right, I was a bit over zealous in my analysis
there!

However, both methods are valid loops (although, mine is not isochronous).
Yours gives a greater maximum number of cycles than mine,too.

Dennis also pointed out that my expression is wrong for the case where Y=0
or X=0. Yes, although you can count Y=0 as Y=256 and X=0 as X=256,and then
it works. I should have mentioned that.

Thanks for the corrections.

Sean

At 10:22 AM 5/7/99 +0800, you wrote:
>Hi Sean,
>
>I think this is not the case, my routine has a "goto $+2" not a "goto
>loop" after the first increment (to be isochronous to 5 cycles per
>loop).  The total cycles should be:
>
>Cycles = (65536 - (hi * 256 + lo)) * 5
>
>Except when hi and lo is zero which is 65536*5 cycles.
>
>regards,
>Reggie
>
>--
>e-mail: rberdin@bigfoot.com
>ICQ#:   31651436
>URL:    http://www.bigfoot.com/~rberdin
>
>
>Sean Breheny wrote:
>> In case anyone wants to use this loop, the more general form is:
>>
>>              movlw x
>>              movwf xf
>>              movlw y
>>              movwf xy
>>              delay(A)
>> aloop        delay(B)
>>              decfsz xf,f
>>              goto aloop
>>              delay(C)
>>              decfsz yf,f
>>              goto aloop
>>
>> Which has the timing expression:
>>
>> total cycles = (770+256*B+C)*Y + (B+3) * X + A + 2
>>
>> In the case given by Reggie, where A=B=C=0:
>>
>> total cycles = 770*Y + 3*X + 2
>>
>> Sean
>>
>> At 09:42 AM 5/7/99 +0800, you wrote:
>> >Hi Scott,
>> >
>> >How about, 5 cycles per loop, doesn't use W:
>> >
>> >        clrf    lo
>> >        clrf    hi
>> >
>> >loop    incfsz  lo,f
>> >         goto   $+2
>> >        incfsz  hi,f
>> >         goto   loop
>
|
| Sean Breheny
| Amateur Radio Callsign: KA3YXM
| Electrical Engineering Student
\--------------=----------------
Save lives, please look at http://www.all.org
Personal page: http://www.people.cornell.edu/pages/shb7
mailto:shb7@cornell.edu ICQ #: 3329174